[XML Schema Datatypes] datatype for strings with language tags

Dear XML Schema working group,

I am a member of the Rule Interchange Format (RIF) working group, which
is part of the Semantic Web activity at W3C.  In our efforts to ensure
compatibility with RDF, we have stumbled upon an issue related to XML
schema datatypes.


First a bit of context:

The core of RIF is a rules language which supports the use of concrete
values (e.g. strings, integers).  Each of these concrete values has a
datatype.  Like the other Semantic Web languages (RDF and OWL) we use
the XML schema datatypes.

However, RDF also defines the notion of plain literals with and plain
literals without language tags.
Plain literals without language tags are sequences of Unicode characters
which denote themselves.
Plain literals with language tags are sequences of Unicode characters
combined with a language tag which is formed according to [RFC-3066].

In order to ensure compatibility with RDF we need to support both kinds
of plain literals in RIF.  It turns out that, in RDF, plain literals
without language tags are interpreted in the same way as the string data
type in XML schema, which we consequently use for the representation of
plain literals without language tags.
However, we did not find an XML schema primitive datatype suitable for
representing plain literals with language tags.


My question is the following:

Has the XML schema working group ever considered defining such a
datatype (i.e. strings with language tags)?  Or would the XML schema
working group be interested in developing such a datatype?
Alternatively, do you have a different suggestion for representing
literals with language tags?

We are considering defining such a datatype, and would prefer to comply
with the XML schema datatypes as much as possible.

Thank you in advance for your help.


Best regards,
Jos de Bruijn
-- 
Jos de Bruijn            debruijn@inf.unibz.it
+390471016224         http://www.debruijn.net/
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